The association between health-related quality of life (HRQoL), psychosocial distress, and supportive care is in the focus of patient-centered neuro-oncology. We investigated the relationship between the aforementioned in glioma-patients to evaluate the association of these instruments and determine cut-off values for suitable HRQoL scales indicating a potential need for intervention. In an observational multi-center study, outpatients completed the Distress Thermometer (DT), EORTC Quality of Life Questionnaire (EORTC-QLQ-C30/BN20, HRQoL), and Supportive-Care-Needs-Survey-SF34-G (SCNS). Based on nine EORTC-function and selected -symptom scales items of the questionnaires were matched. Convergent validity of related single items and scores across the instruments was estimated. EORTC cut-off values were calculated. Data of 167 patients were analyzed. The strongest correlation of EORTC-QLQ-C30 and DT was found for cognitive function (cogf), global health status (GHS), emotional (emof), role function (rolef), future uncertainty (FU), fatigue, and between EORTC-QLQ-C30 and SCNS for FU, emof, rolef (r = |0.4–0.7|; p < 0.01). EORTC cut-off values of <54.2 (GHS/QoL) and <62.5 (emof) predicted a DT ≥ 6 (AUC 0.79, 0.85, p < 0.01). EORTC cut-off values of <70.8 (emof) and <52.8 (FU) predicted the need for supportive care (AUC 0.78, 0.85; p < 0.01). Worse EORTC-C30 scores correlate with higher DT and SCNS scores. With this exploratory assessment, cut-off values for EORTC-C30 subscores to predict distress and pathological SCNS-scores could be determined, which could influence patients’ referral to further treatment. However, further prospective clinical trials are needed to confirm the clinical relevance of these cut-off values.